Method of and apparatus for straightening strip steel



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A. B. WILSON METHOD OF AND APPARATUS FOR STRAIGHTENING STRIP STEEL 2 sheets-sheet 2 Filed Dec. 16, 1938 Patented Nov. 2, 1943 METHOD F AND -APPARATUS FOR STEAIGHTENIN G STRIP STEEL Allen B. Wilson, Evanston, lll., assignor to Acme Steel Company, Chicago, lll., a corporation of Illinois Application December 16, 1938, Serial No. 246,024

7 Claims.. (Cl. 153-54) This invention relates to improvements in method of and apparatus for straightening strip metal and the like, and its purpose is to provide improved means by which elongated metal strips may be straightened and flattened. The present invention is an improvement upon that described and claimed in Vthe copending application of Chester M. MacChesney, Serial No. 87,140, led June 25, 1936, and now Patent No. 2,140,533, December 20, 1938.

Strip steel, such as that employed in binding boxes, bales, and the like, and for various other purposes, is rolled in long continuous strips and it is frequently found that when it comes out of the mll it has a lateral curvature or a multiplicity of lateral curvatures in its own plane, called camber," which interferes with the winding of the strip in a coil and prevents its use for most purposes. It has been necessary heretofore to scrap a great deal of this imperfect strip metal and quantities of this imperfect material are frequently returned by customers.

The present invention involves the discovery that this lateral curvature in strip steel and the like may be removed by a process of progressive stretching of the metal longitudinally accompanied by a lateral bending thereof, according to which different longitudinal portions of the metal are subiected successively to stretching operations while being bent transverselv, after.

which the strip is rolled to put it in a at condition. By following this general procedure, it has been found that camber may be effectively removed from strip metal. leaving the edges of the strip parallel to each other and in the same plane with the intermediate portions, without creating excessive tension in the metal. thus making the process particularly applicable for the treatment of strip metal of light gauges.

According to one embodiment of the invention, the elongated metal strip is run endwise under tension through a series of rolls, one of which is provided with a convex peripheral surface adapted to elongate the intermediate portion of the strip and to bend it transversely while a succeeding roll is shaped to stretch the lateral edge portions of the strip without substantially aifecting the intermediate portion, and

a nal roll ilattens the strip and effects some stretching of portions thereof, thus producing a ilat strip having edges of equal length. The present invention may be used for preparing strip metal for various purposes where a iiat strip having parallel edges of equal length is required, such as in the manufacture of Venetian blind slats, which may be produced by the method described and claimed in my copending application Serial No. 239,229, filed November 7, 1938, and now Patent No. 2,294,434, Sept. 1, 1942.

Other features and advantages of the invention will appear more fully hereinafter.

The nature of the invention will be understood from the following specication taken with the accompanying drawings, in which one example of the improved method is disclosed in connection with one form of apparatus adapted for use in practicing the method. In the drawings,

Figure 1 shows a somewhat diagrammatic side elevation of the improved apparatus which is employed in the straightening process of the present invention;

Fig. 2 shows an enlarged top plan view of a portion of the apparatus illustrated in Fig. 1;

Fig. 3 shows a side elevation of the apparatus illustrated in Fig. 2;

Fig. 4 shows an enlarged detailed section on the line 4 4 of Fig. 2;

Fig. 5 shows an enlarged vertical on the line 5-5 of Fig. 4;

Fig. 6 shows an enlarged vertical section taken on the line 6--6 of Fig. 4;

Fig. 'I shows an enlarged vertical section taken on the line 'l-l of Fig. 4; 1

Fig. 8 shows an enlarged transverse section through the metal strip after it has passed through the rst convex roll which stretches the intermediate portion of the strip and imparts a bowed cross section thereto;

Fig. 9 shows an enlarged transverse section through the metal strip after it has been passed through a succeeding roll which stretches the lateral edge portions of the strip without affecting the intermediate portion thereof; and

Fig. 10 shows an enlarged transverse section through the strip in its final form after it has been flattened by rolls having cylindrical surfaces.

In Fig. 1 of the drawings there is illustrated diagrammatically one form of the apparatus which is capable of use in practicing the present invention. As there illustrated, the elongated metal strip I5 is shown as being withdrawn from a reel I6 and moved in the direction of the arrow I1 by means of a series of driven friction rolls I 8 which are comparatively large in diameter and which are arranged in zig-zag fashion so that the strip is compelled to follow an irregular path in passing through this series of rolls, thereby obtaining a large area of contact between the strip 0f the Surface of each roll. The strip I5 then section taken passes in zig-zag fashion through a series of parallel straightening rolls I5 which are comparatively small in diameter and which operate as idler rolls arranged with their axes in one plane so that the metal strip may be passed on opposite sides of successive rolls to cause it to follow a zigzag path as'it passes through them. After'leaving the straightening rolls I9, the strip I5 passes through or laround a series of friction-rolls 2l which are power driven and which pull the strip under tension through the straightening rolls I5. Upon emerging from the rolls 20, the strip I5 is wound upon. a reel 2| which maintains the strip under suificient tension in the process of winding to hold it in contact with the friction rolls 20.

The friction rolls 24 are preferably slightly larger in diameter than the-friction mils Il, if the rolls of the two series are driven at the same angular speed, or the rolls 20 may be driven slightly faster than the rolls I 8, sothat the peripheral speeds of the rolls 25 are greater than the peripheral speeds of the rolls I8, thus creating'a substantial tension inl a longitudinal direction in the strip I5 as it passes through the intervening straightening rolls I9. Some slippage is provided in the driving mechanism of the friction rolls so that the tension created in the strip I5 is not sufiicient to elongate the strip generally throughout its width and the result is that as the strip passes through the rolls |8,vthe tension therein is sufiicient to effect the progressive stretching of the different portions of the strip in a longitudinal direction,` as referred to above, until the shorter edges of the strip are the same length as the opposite longer edge portions. A brake is applied to the supply reel I8 to prevent the metal strip from being withdrawn therefrom too rapidly, thereby maintaining it in close contact with the rolls Il, and the driving mechanism which is connected to the winding reel 2| is provided with a friction clutch which is adapted to slip when required so that if the reel 2| be driven at a greater speed than the friction rolls 20, according to the preferred practice, the friction clutch may slip and at the same time maintain the strip sumciently taut between the rolls 20 and the reel 2| to bring about a tight winding of the strip in the coil while at the same time maintaining the strip in close contact with the surfaces of the rolls 25.

The rolling and straightening apparatus is illustrated in' detail in Figs. 2, 3, 4, 5, 6 and '1,

where it is shown as comprising a frame 25 having mounted thereon bearings 26 in which is iournaled a shaft 21. This shaft is provided with a brake drum 25 engaged by a friction brake strap 29 and the end of the shaft has secured thereon the reel I on which the metal strip I5 to be straightened iswound. This drum I6 has a disk 30 at one side thereof and its periphery is slotted as shown at ||n for engagement by the inner end of the strip wound thereon. As the strip is unwound from the drum I5, the brake 28-29 prevents the drum from unwinding too freely and the brake strap 25, which is held against rotation, is capable of adjustment for the purpose of regulating the resistance which is interposed to the unwlnding of the strip. The friction drums I8, about which the strip l passes in advance of the straightening rolls I5, are carried by a frame Il which is mounted upon the floor or base 32 by which the frame 25 is carried. This frame 3| comprises 1ongitudinal frame members 3|l carrying bearings 33 in which are iournaled a plurality of transverse shafts 34 on the projecting ends of which assaass the friction rolls Il are secured. These mils Il are of sumcient width to accommodate any width of strip metal to be straightened and they are provided at the edges with flanges Il* to retain the metal strip in position thereon. The shafts 34 are so positioned that the rolls Il have an irregular zig-zag arrangement which causes the metal strip Il to follow a corresponding sinuous path in passing through these rolls while also *compelling the strip to contact with a considerable portion of the surface of each roll.

The shafts 54 are driven from a parallel shaft. 35 joumaled in bearings secured to the under side of the frame members Il.. Thisshaft 35 carries a pinion J5 which meshes with two gears l1 xed on two of the shafts 54. These two gears l1 mesh with other gears 31 on the other shafts 34, as shown in Fig. 3, so that when the shaft 35 is driven, as hereinafter described, all of the shafts I4 are driven in the proper directions to advance the strip I5 through these rolls when the apparatus is in operation. l The end of the frame 3| carries a transverse member 38 of channel form which is provided with a slot 38* in its upper flange for engagement by a pair of pins 39 which extend vertically and have rollers 4l Journaled thereon. These rollers 4I are positioned on opposite sides of the strip I5 and are adapted'to maintain the strip in proper alignment with the straightening rolls I9 as the strip moves through the apparatus. The pins 3l are capable of adjustment in the slot Il* to cause them to`align properly with the straightening rolls and to accommodate strips of various widths and they may be clamped in the desired adjusted positions.

'I'he rolls 2|I, through which the strip I5 passes after passing through the straightening rolls Il, are xed on the ends of a plurality of parallel shafts 43 which are journaied in bearings' u carried by the longitudinal frame members 45u of another frame 4l which is carried by the base 32. The rolls 2lare provided with flanges 20` to retain the strip I5 in position thereon and they are arranged in zig-zag fashion like the rolls Il so that the strip I5 coacts with a considerable portion of the periphery o f each roll. The shafts 43 are driven by a shaft 46 which has a pinion 41 fixed thereon and arranged to mesh with two of the gears 4l which are secured upon the outer ends of the shafts 43. The gears 48 mesh with each other on thev various shafts 43 in such a manner that the shafts 43 are all driven in the proper directions to advance the strip I5 through the machine when the shaft 45 1s actuated as hereinafter described.

The straightening rolls Il are carried by an intermediate frame 49 which is in the form of a heavy angle bar having its ends resting upon and secured to the frames 3| and 45, as shown in Fig. 3. The frame 45 ha; an upwardly extending ange 45a, as shown in Figs. 5, 6, and 7, in which are secured the inner reduced ends 5l* of a series of stationary spindles or axles 54 upon which the straightening rolls I9 revolve.

These spindles have enlarged collars 50" which.-

coact with the outer faces of the vertical portions 45 of the intermediate frame member and their inner threaded extremities are engaged by nuts 5| by which the spindles are clamped securely in position on the frame. A washer 52 seats against the outer end of each straightening roll I9 and this washer and the roll are held on the spindle by a nut 53 engaging the redu'ced threaded portion 50c of the spindle. Each spindie terminates in a reduced portion 50d which nts in an aperture in a frame member 54 extending parallel to the frame member 49a. At suitable intervals, the frame member 54 is apertured for engagement by set screws 55 by which the member 52 may be clamped in position on certain of the spindles 50.

'I'he first straightening roll I9 of the series, proceeding toward the left from the right-hand end of the series as viewed in Fig. 4, is of the form shown at I9* in Fig. 5. This roll has a convex peripheral surface I9b and is provided internally with bushings 55 which revolve upon one of the spindles 50. As the strip l is pulled through the straightening rolls, the roll I9 engages the strip and stretches the intermediate portion thereof so that it is bowed transversely, as shown at I 5 in Fig. 8. In this operation, the intermediate portions of the strip are stretched longitudinally while the lateral edge portions have little or no stretch imparted to them.

'Ihe second straightening roll of the series is of the form shown at I 8? in Fig. 7 where the peripheral surface I9d of the roll is in the form of two truncated cones tapering inwardly from the ends of the roll. This roll like the others is provided with bushings 55 revolving on one of the spindles 50 and, as the strip I5, having the bowed cross section shown in Fig. 8, advances from the roll I9, the direction of its convexity automatically reverses itself and it passes over the roll I9 with the result that the tapered surfaces I!!d stretch the lateral edges of the strip and cause them to be deflected upwardly, as shown at I5b in Fig. 9. These lateral edge portions which are thus stretched while the intermediate portion of the strip remains in the condition it was in after passing the roll I9, are united with the intervening portion of curved cross section along angular lines I5 which form shoulders or ribs extending throughout the strip.

After passing over the roll I9 the metal strip passes over and under the remaining rolls I9 of the series which are in the form shown in Fig. 6, each of the rolls I9 having a cylindrical outer surface I9'-, so that as the strip I5 passes through these rolls the longitudinal portions I5@ are elongated and the entire strip is iiattened to the condition shown at I5 in Fig. 10, wherein the lateral edges of the strip are parallel and of equal length.

The apparatus described above is driven by an electric motor 60 which has a shaft 6I provided with a relatively fixed pulley 62. A belt B3 passes over this pulley and over another pulley 64 which is secured upon the projecting extension of the shaft 46 previously described. The adjacent end of this shaft 46 is journaled in a bearing box 65 and a pulley 66 is secured on the shaft adjacent to the frame 40. A belt 61 passes around the pulley 66 and around another pulley 68 which is secured upon the shaft 35 previously referred to, In this way, the power derived from the motor 66 is utilized to drive both of the shafts 35 and 46 which operate the friction rolls I8 and 20, respectively. Since the rolls 20 are slightly larger in diameter than the rolls I 8, for example, a few thousandths of an inch, the rolls 20 tend to pull the strip I5 through the straightening rolls I9 at a greater speed than that with which the strip is supplied to the rolls I9 by the rolls I 8, and in order to retain the desired degree of tension in the strip I5, While it is in engagement with the straightening rolls I9, by

this method, without unduly stretching or breaking the strip. some slippage of the belt 61 on the pulleys 66 and 68 is permitted during the operation of the machine.

In order to regulate the slippage for maintaining the desired tension in the strip, means are provided for adjusting the tension of the belt 61. 'I'his means includes a roller 10 which revolves on a pivot pin 1I carried by the free ends of al pair of arms 12 having their lower ends pivoted on a shaft 13 carried by a bracket I4 secured on the frame 3I. The shaft 13 has secured thereon a downwardly extending arm 15 which is apertured at its lower end for engagement by a stud 18 having its inner end threaded into a hole in an adjacent frame member. A nut 11 threaded on the stud 16 is adapted to engage the outer face of the arm 15 to limit the outward movement of this arm and the corresponding upward movement of the roll 1I).

As a further means of regulating the tension of the belt 61, a bell crank lever 18 is pivoted at 19 on a bracket 80 carried by the frame 45 and one arm of this bell crank lever is bifurcated to receive a roller 8I which is rotatably mounted therein and adapted to rest upon the upper side of the lower stretch of the belt, as shown in Fig. 3. The upstanding arm of the bell crank lever 18 is apertured for engagement by a stud 82 which is threaded into the adjacent vertical member of the frame 45. vA nut 83 engages the stud 82 to limit the outward swing of the upper arm of the lever 18 and thereby limit the downward movement of the roller 8I, which coacts with the belt. By regulating the extreme positions of the rollers 10 and 8|, the slippage of the belt 61 may be regulated as desired.

The shaft 4I, which drives the belt 61, also has xed thereon a grooved pulley 85 which drives a multi-strand endless belt 86 mounted to drive a larger pulley 81 rotatably mounted on the `shaft 88 on which the winding reel 2| is fixed. A friction clutch 89, actuated by a spring 90, forms a driving connection between the shaft 88 and the pulley 81 so that the desired tension may be maintained in the strip between the friction rolls 20 and the reel 2l while permitting some slippage as described above. The shaft 88 is journaled in bearings carried by an auxiliary frame 9|.

With the apparatus described above, metal strips I5 of varying widths may be run through the rolls I8, I Stand 20 to effect the elimination of camber in the strips. The rollers I9 are preferably of substantially the same width as the strip being rolled, but the width of these rollers may be varied, as desired, by removing the spindles 50 from the frame member 49 and replacing them with other spindles of different length carrying other rollers I9 of different width. In advance of the roller I9, previously described, there is preferably provided a roller I9 which is equipped at its ends with radial disks I9I adapted to guide the strip I5 as it passes into the series of rolls I9. After passing between the disks I 9', the strip passes beneath the roller I 9' and the intermediate portion thereof is elongated while the lateral edge portions preferably remain substantially unchanged or only slightly stretched, thus giving the strip the bowed cross section shown at I5"L in Fig. 8. The strip then passes over the next roll of the series, being a roll I9 of the form shown in Fig. 7. As the strip approaches this roll, the direction of the buckle in the metal will be reversed from that which it has when it emerges from the roll I9* so that the strip will be bowed upwardly as it passes over the roll I9 and its lateral edges will be stretched by the inclined surfaces |94 of this roll, thus causing the lateral edges to be flared upwardly with respect to the intermediate bowed portion, as shown at l5 in Fig. 9. By this progressive stretching of the metal, ilrst in one longitudinal portion and then in another, the shorter edge portions are stretched to a greater extent than the longer edge portions and al1 portions of the metal are stretched sumciently to cause the edges to become parallel to each other and of the same length. The ilnai stretching and ilattening operation is effected by the series of cylin# drical rolls of the form shown in Fig. 6 which reduce the metal strip from a form having the irregular cross section, as shown on the magnifled scale in Fig. 9, to the ilat form shown in Fig. 10. This dat strip may then be wound in regular fashion upon the winding'reel 2l after passing through the rolls 2l.

Although one embodiment of apparatus embodying the invention and one example of the improved method have been illustrated and described, it will be understood that the invention may take various other forms and may be practiced in various ways within the scope of the appended claims.

I claim:

l. The method of removing lateral curvature from an elongated metal strip,`which comprises the steps oi running the strip endwise under tension along a sinuous path and simultaneously eiiecting the permanent stretching longitudinally of the intermediate portion of the strip and then the permanent stretching longitudinally of the lateral portions of the strip until the entire strip has been stretched longitudinally throughout its length. y

2. 'I'he method of removing lateral curvature from an elongated metal strip, which comprises the steps of permanently stretching longitudinally one longitudinal portion of the strip and then progressively effecting the permanent stretching in succession of other longitudinal portions of the strip until the strip has been permanently stretched longitudinally throughout its width and throughout its length.

3. The method of removing lateral curvature from an elongated metal strip, which comprises the steps of running the strip endwise along a sinuous path while under tension and effecting the stretching longitudinally in succession of different longitudinal portions oi' the strip until the strip has been permanently stretched longitudinally throughout its width and throughout its length.

4. 'Ihe combination in apparatus for removing lateral curvature from an elongated metal strip, of a series of rolls through which the strip is adapted to travel, and means for moving the strip under tension through said rolls. said rolls having peripheral surfaces shaped to effect the successive and permanent longitudinal stretching of different longitudinal portions ofthe strip throughout the length of the strip and to effect the longitudinal stretching of successive longitudinaily displaced portions of the strip passing therethrough.

5. The method of removing lateral curvature from an elongated metal strip, which comprises the steps of permanently stretching the intermediate portion oi' the strip longitudinally throughout the length of the stripand then permanently stretching longitudinally the lateral portions of the strip throughout the length of the strip, said stretching operations being carried on until all portions of the strip are permanently stretched longitudinally.

6. 'I'he method of removing lateral curvature from an elongated metal strip. which comprises the steps of permanently stretching the intermediate portion oi the strip longitudinally, then permanently stretching longitudinally the lateral portions oi' the strip, and then permanently stretching longitudinally portions of the strip between the ilrst and second named portions, said stretching operations being carried on until all portions of the strip between its edges are permanently stretched longitudinally.

7. The combination in apparatus for removing lateral curvature from an elongated metal strip, of a set of straightening rolls through which the strip is adapted to travel, some of said straightening rolls havingperipheral surfaces shaped to effect the permanent stretching throughout the length of the strip passing thereover of all longitudinal portions of the strip which are displaced laterally from each other-.Aa power-driven winding reel for moving said strip through said straightening rolls, a' supply reel from which the strip to be straightened is unwound from said ilrst named strip, and s series of friction rolls engaged by said strip between each of said reels and said straightening rolls.

ALLEN B. WILSON. 

